This revised program will consist of four areas. PROJECT I will investigate; a) The intrinsic electrical properties of Purkinje cells at whole-cell, single-channel and molecular biological levels. Single-cell and circuit properties will be studied in the brain stem and thalamus in in vitro slice and isolated brain preparations to determine how these intrinsic properties relate to the network in which they participate; b) Single-cell function under in vivo conditions during behavioral acts such as vibrissae movements, using multiple electrode recording. PROJECT II, which has been completely modified, will examine the morphological basis for the regulation of intracellular calcium concentration in cerebellar neurons. PROJECT III has been rewritten and will study the neuronal mechanisms of motor learning and memory in the oculomotor and cerebellar systems of teleosts and elasmobranches. PROJECT IV will investigate the contributions of cerebellar modular organization to sensorimotor integration through analysis of the signal processing accompanying eye movements elicited by natural visual, vestibular, and proprioceptive stimuli. The questions addressed by the Study Section Review Committee for each of the areas will be answered, in detail, in the introduction to each section.